Pre-Foiled Closures

ABSTRACT

A pre-foiled closure ( 2 ) for engaging over an open end of the container has an openable section ( 18 ) that can be pivoted relative to the non-openable section ( 6 ) of the closure. The openable section carries a foil retainer ( 24 ) which is welded to the foil. The closure is intended to be induction heat sealed to the rim of a container and can be opened by pivoting the openable section ( 18 ). This lifting action tears the foil and removes a portion of the foil attached to the foil retainer. This eliminates the need for a separate ring pull to open the closure.

TECHNICAL FIELD

The present invention relates to pre-foiled closures which arc applied over an opening in a container.

Cartons and plastics containers for drinks and other liquids are frequently sealed by means of an induction heat sealed (IHS) foil that is bonded to a rim of a mouth of the container typically within a spout. The foil closes the mouth opening in order to provide a gas barrier.

By contrast to older style containers sealed with a peelable foil that can be provided with a tab so that the foil can be removed by a peeling action once the overcap has been removed to expose the foil, in the case of modern BAP® pre-foiled closure designs, it is normally necessary to initiate a tear in a bonded foil in order to gain access to the contents of the container. The foil may also have its border bonded between the rim and a portion of the spout as, for example in the applicant's own earlier application. GB 2377701 (SPRECKELSEN MCGEOUGH LTD). 2003-01-22. so that there is no access to the border of the foil for a peeling style of opening.

An example of an older style closure employing a peelable foil is described in EP 1266839 A (PORTOLA PACKAGING LTD). 2002-12-18. In this case a pull tab is provided for assisting the removal of the foil membrane. Peelable IHS foils are thicker, may have more layers, and are heavier and therefore more expensive than tearable IHS foils.

BACKGROUND ART

It has been suggested in GB 2350105 A (SPRECKELSEN MCGEOUGH LTD). 2000-11-22. that a plate be sealed to and support the foil. The plate is mounted to the overcap so that it can swivel relative to the overcap during the opening process. The plate is provided primarily to support the foil to prevent it being ruptured by gas pressure when the closure is used with pressurised fluids. However, opening of the overcap also initiates a tear in the foil membrane and breaks the seal.

In GB 2108464 (CONTAINER CORPORATION). 1983-05-18. there is described in relation to FIGS. 6 to 8, a container defining an opening, a foil membrane closing the opening and having a border adapted to be induction heat sealed to a rim of the container, and an overcap having a formation terminating in an edge bonded to the foil to define a removable portion of the foil. The formation is a cylindrical inner rim of a hinged lid, which is closed so that it is aligned with and directly supported by the rim of the container. This results in a strong seal that is difficult to break and the foil may remain bonded to either rim once the lid is lifted. The container, foil and overcap are assembled in a single operation, which results in assembly problems.

In the technical field of carton fitments as opposed to pre-foiled closures which are applied over an opening in a container to which this invention relates, WO WO 93/13998 A (CAP SNAP CO.). 1993-07-22. describes a closure comprising a spout defining an opening and a foil membrane closing the opening, the closure having an openable section with a foil retaining formation terminating in an edge bonded to the foil to define a removable portion of the foil membrane, the foil membrane also being bonded to a non-openable section of the closure before application to a container. This closure is described by Cap Snap as an optional embodiment of FIG. 5 in which the foil retaining formation is a bottom edge of a plug skirt that must be lifted up through a spout to open the closure. Cap Snap also teaches the use of a foil disk of greater diameter than a flange of the fitment that defines the spout. Only one side of the Cap Snap foil is used in the bonding operations. The reader is not taught how to create the weld to the foil without welding the skirt to the adjacent spout or how the closure can be opened. Considerable problems would also be presented during handling of this closure by the presence of an unsupported and unprotected foil border beyond the flange. The closure would also leave the edge and other side of the foil exposed to the contents of the container.

The larger the mouth of the container, the more difficult it is to initiate a tear in the foil membrane. These issues have been discussed in GB 2404916 (SPRECKELSEN MCGEOUGH LTD). 2005-02-16. which teaches design improvements for the mounting of a supporting leg of a pull ring in order to reduce the pulling force required to initiate the tear.

DISCLOSURE OF INVENTION Technical Problem

The present invention addresses the technical problems that arise with pre-foiled closures in the opening of the foil without the littering problem of removable pull rings and foil and without the need for undue force, skill, knowledge or dexterity on the part of the user.

Technical Solution

The closure of the present invention is characterised in that the closure has means for engaging it over an open end of a container; in that the foil membrane is held inside the closure in order to provide a border adapted to be induction heat sealed to the container; and in that the openable section is pivotable relative to the non-openable section of the closure.

The same principle can be employed with a small plastics closure in which the openable section is the whole of an overcap or a large can or container end in which the openable section is a section of an overcap that is pivotable relative to the remainder.

Preferably the foil membrane is bonded to a land on the non-openable section close to an edge of the opening in order to create a region of foil which is stretched between the land and an adjacent part of the foil retaining formation during the opening process to create an initial tear in that stretched region. Preferably the stretched region is opposite a hinge about which the openable section pivots open. In order to create that tear, it may be desirable to provide at least one foil tearing tooth between an edge of the opening and the land.

The edge of the formation may be continuously or intermittently welded to the foil. The formation is preferably a depending wall having an edge with a radius of less than 0.3 mm, preferably 0.1 mm.

Advantageous Effects

As can be seen from the prior art discussed above, the idea of opening a lid and removing the foil at the same time is a desirable idea. However, its implementation has not proved straightforward as prior art proposals have proved to be unopenable in practice.

In use, removal of the openable section brings with it the removable portion of the foil. This eliminates littering issues associated with removable ring pulls.

The closure in accordance with the invention can be moulded very simply as there are no complex ring pull structures requiring the use of separate retractable metal cores which increase the cycle time of the mould.

The energy needed to weld the edge to the foil is modest because the edge is so fine. This is in contrast to the energy absorbed to weld a plate to the foil as in GB 235015 A (SPRECKELSEN MCGEOUGH LTD). 2000-11-22.

In an embodiment of the closure in which the overcap is clipped in position and has a peak by means of which the user can lift the overcap, the formation preferably has a shape which converges to a tip aligned with the peak.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be well understood, five embodiments thereof will now be described, by way of example only, with reference the accompanying diagrammatic drawings, in which:

FIG. 1 is a perspective view of a spout as moulded for a closure in accordance with a first embodiment of the invention;

FIG. 2 is a view from below of the spout of FIG. 1;

FIG. 3 is a section on line 3-3 in FIG. 2 showing the closure with a foil membrane applied;

FIG. 4 is a perspective view of a variation of the first embodiment of the closure shown secured to a can and in an open condition;

FIG. 5 is a perspective view of the spout and overcap in an open condition showing two alternative designs for the edge of the formation in accordance with a second embodiment of the invention;

FIG. 6 shows a plan view of the overcap and spout of FIG. 5;

FIG. 7 shows a section on line 7-7 of FIG. 6

FIG. 8 shows a plan view of the second embodiment of the closure after it has been assembled into a closed, foiled condition;

FIG. 9 shows a section on line 9-9 of FIG. 8;

FIG. 10 shows a plan view of an overcap and spout in accordance with a third embodiment of the invention;

FIG. 10 a and 10 b shows plan views as in FIG. 10 showing variations of the profile for the shape of the foil retainer;

FIG. 11 shows a perspective view of a closure for a can end in accordance with the fourth embodiment of the invention;

FIG. 12 shows a section through an edge of the overcap of FIG. 11;

FIG. 13 shows a fifth embodiment of a closure for a can end; and

FIG. 14 shows a section through an edge of the overcap of FIG. 12.

The present invention can be implemented as a one-piece spout overcap for use over an open mouth of a container as shown in FIGS. 1 to 4 and 11-14 or as a spout and overcap combination as shown in FIGS. 5-10.

FIRST EMBODIMENT

A closure 2 for an open end of a container is made up of a spout overcap 4 to which a foil membrane 20 is induction heat sealed prior to the presentation of the closure to an open mouth of a container.

The foil membrane 20 is a double sided foil, which is a thin aluminium foil coated on one side with a plastics material compatible with the material from which the spout overcap is moulded and on the other side with a plastics material compatible with the material of the container. The membrane 20 may also be or contain a plastics barrier membrane. For example the membrane may be a laminate that contains a plastics barrier layer.

The spout 4 as shown in FIG. 1 can be moulded in one piece from relatively rigid plastics materials such as HDPE or PP. LDPE would not be suitable as it would be too flexible. The spout 4 consists of a non-openable section in the form of an overcap 6 with a skirt 8. An opening 10 is defined in the non-openable section and has an edge 12 shaped to provide a convenient pouring opening. An openable section 18 is moulded in a vertical position as shown in FIG. 1 and merges with the overcap section at a hinge 22 formed by a thinner plastics web between a root of the openable section and the non-openable section. By moulding the spout in this configuration, it can be made efficiently using a three-part mould which has two laterally separable parts to create the upper side of the overcap. These upper parts define between their facing surfaces, a cavity for creating the openable section 18. The openable section 18 carries a foil retaining edge formation 24 that is shaped to fit inside the opening 10. A flange 26 at the remote end of the openable section is angled relative to the remainder of the section to enable it to be gripped and lifted. This flange 26 sits outside the skirt 8 when the openable section has been pivoted down into the same plane as the rest of the overcap.

FIG. 2 shows the underside of the overcap after the openable section 18 has been closed down. On this surface of the overcap, a peripheral broad land 28 is formed around the inside edge to retain the foil membrane 20 inside the spout. A land 30 is also provided around the periphery of the opening 10. This land 30 must be close to an edge of the opening 10 at least opposite the hinge 22.

As moulded, these lands are not perfectly flat but have a raised ridge 32 along one edge. When the induction heat sealing foil membrane 20 is applied over the surface of the lands 28, 30, it comes into contact with the ridge 32 and it is this which melts first and welds to the plastics coating of the foil 20. In this way, less energy is consumed as a world can be created simply by supplying sufficient energy to melt the bridge and then allowing the melted plastic to flow across the land. This also ensures that the rest of the moulding is not damage during the pre-foiling.

A series of foil tearing teeth 19 are formed around the edge 12 of the opening 10. The teeth do not need to reform all around the opening but it may be desirable to have at least one foil tearing tooth in the region opposite the hinge and between a portion of the land 30 close to the edge of the opening in that region as this is where an initial tear in the foil membrane will be made as the openable section is pivoted open.

In the variation of FIG. 4 designed for use with a PET container having the shape of a standard 350 ml can. The openable section 18′ extends across the entire width of the spout overcap 4 and has a hinge 22 at the edge of the overcap by means of which it is pivoted open. The openable section 18′ has a liftable tab 33 moulded into a recess in order to facilitate the pivoting of the openable section relative to the non-openable overcap section 6. As shown in the drawing, the foil retainer 24 surrounds an opening 25 directly above the opening 10 so that the foil 20 can be seen. This opening 25 can be covered in use by a plug. In this variation the opening 10 in the overcap 6 is shown as tear drop shaped converging to a point towards the centre of the can mouth opposite the hinge 22.

Assembly and Use of the First Embodiment

Spout overcap components 4 are moulded as shown in FIG. 1 and removed from their moulds. The openable section 18 of each component is then folded down so that the thin foil retaining formation wall 24 snap fits into the opening 10. A foil disc 20 is then placed inside each overcap to cover the entire lower surface. An anvil holds the disc in contact with the lands 28, 30 of the surface while the assembly is in an induction heat sealing chamber and subjected to a magnetic field which create sufficient heat in the aluminium foil to weld foil membrane to the lands 28 and 30 to create a pre-foiled closure. The edge of foil 20 is inside the skirt 8 and is therefore protected from damage during transit of the pre-foiled closures.

As with earlier BAP® closures, the closures 2 can be sterilised in the closed, foiled condition and supplied to a factory where they will be fitted to containers.

The pre-foiled closure exposes a border of foil opposite the land 28 that can be bonded to a rim of a container. Because this border of foil 20 will be welded on both sides, it will be extremely difficult to separate this border from the container without considerable force. This weld also ensures that an exposed aluminium edge within the foil 20 is kept securely away from the contents of the container. There should be no part of the container which bonds to the foil opposite the foil retainer 24 and therefore this bond will be preferentially weaker than the bond at the rim of the container.

When the user wishes to open the closure 2, the openable section 18 is gripped by the flange 26 and pivoted about the hinge 22. This causes the foil membrane 20 in the region between the land 30 and an adjacent part of the foil retaining formation 24 opposite the hinge (in this version adjacent the outer edge of the overcap) to stretch and come into contact with the foil tearing tooth 19 which will initiate the tear if the stretching does not. In order to design closures that require minimal force to open them, it is desirable to have only a relatively narrow bridge of foil in this stretched region between the foil retainer and a part of the foil which is bonded to the non-openable section. In order to achieve an opening pressure in at least this stretched region of the foil, it is desirable that the lifting force be applied to a relatively small area and this can be achieved by making the opening pointed and using a pivoting action to lift the foil retainer.

In the variation shown in FIG. 4, the user grasps the pull tab 33 and lifts it. This will create a significant opening pressure on the foil in a stretched region between the foil retainer 24 at the point of the tear drop shaped opening 10 in the middle of the container opposite the hinge 22. This region is limited by the closely adjacent land 30 and may contain cutting teeth 19 over which the foil will be stretched to puncture it. Once the foil is torn, the openable section 18′ can pivot about the hinge 22. This will also stretch the remainder of the foil 20 in the region between the non-openable section and the land 30 close to the edge of the opening so that the tear will propagate around the opening resulting in a portion of the foil 20 enclosed by the wall 24 being lifted out of the opening 10 with the pivoting openable section 18′. This ensures that there is no littering.

SECOND EMBODIMENT

The spout and overcap embodiments will now be described with reference to FIGS. 5 to 10.

A closure 2 for fitting to a container (not shown) consists of a spout 40 connected to a flip-top overcap 60 by a hinge 80. The spout 40 constitutes the non-openable section of the closure 2 and the overcap 60 the openable section. The spout 40 has a cylindrical wall portion 120 defining an opening 10 and a base 140. The cylindrical wall portion 120 terminates in a pour lip 160. A sealing rib 180 is formed around an inner surface of the side wall 120 in order to seal against a valve in the overcap 60. A series of foil tearing teeth 19 are formed around the opening 10.

A foil membrane 20 is scaled across the opening 10 in the spout 40. A border 220 of the foil membrane 20 is welded by induction heat sealing to the base 140 of the spout.

The structure of the spout 40 is otherwise as described in the applicant's own earlier application GB 2377701 A (SPRECKELSEN MCGEOUGH LTD). 2003-01-22. and BAP® closures manufactured in accordance with designs based on that technology, except for the significant omission of a removable portion that is typically moulded across the opening 10 in the spout. Such a removable portion with its associated ring pull adds considerably to the cost and expense of the spout mould or spout portion of a hinged mould. The remaining details of the spout construction will not therefore be described further as they will be familiar to the skilled reader.

The overcap 60 is also substantially as described in that earlier specification. The overcap has a top wall 300, a side wall 320 and a peak 34 opposite the hinge 80. A cylindrical valve 36 depends from the inside of the top wall 300 and is positioned so that its outer surface will engage with and seal against the sealing rib 180 inside the side wall 120 of the spout 40. The overcap of the present invention however differs in that there is an additional foil retaining formation, in this case a cylindrical wall 400 that acts as a foil retainer. The foil retainer 400 depends from the top wall 300 of the overcap 60 inside the valve 36. The foil retainer 400 terminates in an edge 42 that is formed with a fine radius of 0.3 mm or less preferably 0.1 mm. The thickness of the wall 40 tapers towards the edge 42. The height of the foil retainer 400 is such that the edge 42 will just touch an upper surface of the foil membrane 20 when the overcap 60 is closed over the spout 4. When the edge 42 is in contact with the foil 20, it will define and enclose a circular portion of the foil membrane 20.

The edge 42 may be continuous as shown in the major portion of the edge 42 in FIG. 1. The edge 42 may also be crenellated as illustrated at 44. The edge is therefore discontinuous with short sections 46 separated by cut-outs 48. Only the sections 46 of the edge will weld to the foil membrane 20. It will be appreciated that the shapes of the cut-outs 48 are to be designed to facilitate moulding and tearing.

The foil membrane may be weakened in the region of the edge 42 to facilitate tearing. This weakening can be created by a laser process. It is preferable to avoid this step but it may be necessary for thicker foils or where the edge 42 cannot be moulded sufficiently fine.

An arrowhead 50 is moulded as a depression in a flat top surface of the top wall 300 in order to point to a centre of the peak 34. This arrowhead directs the consumer to the peak in order to indicate the point at which the closure should be opened. Forming the arrowhead as a depression facilitates use of the closure by blind or partially sighted consumers.

A breakable tab (not shown) may be formed between an edge of the overcap and the spout to facilitate visual tamper evidence. Such a breakable tab must be removed before the overcap can be lifted. Other standard forms of tamper evidence such as a band or strip around the overcap may be adapted for use with this closure.

THIRD EMBODIMENT

FIG. 10 shows an alternative embodiment of the foil retainer 400 but is otherwise identical to the previously described embodiment. As shown in FIG. 10, the formation 400 is not a cylindrical wall but is shaped to converge to a narrower tip 52 aligned with the centre of the peak 34.

Other variations for the shape of the formation are shown in FIGS. 10 a and 10 b. In these designs the formation 400 has a shape which defines tips 52′ spaced to either side of the peak 34. These designs have been found to be more effective in tearing out the enclosed portion of foil with minimal effort.

Method of Assembly and Use of the Overcap and Spout Embodiments

It will be appreciated that the spout and overcap embodiments described can be moulded readily in one piece with a mould that forms the spout and overcap together in an open condition as shown in FIG. 5. The closure 2 is assembled by pivoting the overcap 60 about the hinge 80 so that the valve 36 is engaged inside the spout 40. In this closed condition as shown in FIG. 9, a foil membrane 20 is placed in the base 140 of the spout and induction heat sealed to the spout. The induction heat sealing process will weld the foil to the areas of plastics material that it is touching when the placing pressure is applied. Therefore, the border 220 of the foil will weld to a horizontal surface of the base. The edge 42 or those spaced portions of it 46 which touch the foil 20 will also weld to it. Limiting the area of contact between the foil and the plastics of the spout 40 and edge 42 reduces the amount of energy used to weld the foil and reduces the effort to tear it later.

As with earlier BAP® closures, the closures 2 can be sterilised in the closed, foiled condition and supplied to a factory where they will be fitted to containers.

When a container that has been closed with a closure as described is received by the consumer, it can be opened by the application of a lifting and pivoting force applied to the peak 34 of the overcap at the position indicated by the arrow 50. On first opening the closure, there will be a degree of resistance as the foil 20 is lifted and stretched by the formation 400. This lifting force will eventually tear the foil adjacent the edge 42. As the foil is ruptured, there will be an audible pop. This provides consumer re-assurance that the closure has not been tampered with.

When the overcap 60 is pivoted fully open, the space within the foil retainer 400 will normally be covered by the enclosed portion of the foil which has been removed during the opening process. The foil may also be torn by the teeth 19 at the edge of the opening 10.

In the embodiment of FIG. 10, the lilting force applied by the user to the peak 34, initially creates a tear at the tip 52 at which the force is concentrated. The tear will then propagate in both directions around the edge 42 resulting in a droplet shaped enclosed portion of foil being removed with the overcap. A similar effect will be produced using the profiles of FIGS. 10 a and 10 b. Shaping the edge 42 in one of these ways is particularly desirable in applications with larger closures and thicker foils.

In most cases, it will be possible to dispense the contents of the container through the opening created by removal only of the portion of the foil 20 that is enclosed by the edge 42. However, the remaining region of the foil (if any) across the opening 10 may be pushed into the container to clear the entire opening 10.

Since the removed portions of the foil 20 are retained in the closure, littering issues are eliminated.

It will be appreciated that the exact tearing propagation will depend on the force applied during the opening process and the utility of the closure as described is not dependent on any particular tearing pattern.

The closure can be resealed by the consumer as with the existing BAP® closures. Different shapes and designs of the overcap can readily be implemented for brand differentiation purposes. The construction of the present invention therefore retains all the consumer attributes of the earlier closures but allows a simpler mould and a lighter weight closure. The invention therefore makes a closure that is suitable for applications which are of greater price sensitivity.

Can End Embodiments

FIGS. 11 to 14 relate to an implementation of the invention in which a single piece moulded closure 600 (as opposed to a two piece moulded or hinged unit) is designed to replace the whole of an end of a cylindrical can 61, for example a drinks can or bottle made of thermoformed plastics material. The can is essentially cup shaped and has an opening which is closed by the closure 600.

The closure 600 comprises an overcap 62 having a flat top 64 and a depending skirt 66, and a foil membrane disc 68 held inside the overcap by means of a foil retaining formation 70 in the form of an annular ridge or land that is formed on an inner surface of the top 64. The foil retainer 70 terminates in an edge 72 that is bonded to the foil 68.

An edge of the skirt 66 has a bead 74 formed around its internal surface in order to provide means by which the overcap can be engaged over the can end to hold it in position during assembly. The closure 600 is sealed to the can end by induction heat scaling of a border of the foil 68 to a rim of the can.

The overcap 62 also has a section 800 that is adapted to be torn from a remainder of the overcap to create a drinking or pouring opening. The section 80 carries an arcuate section 82 of the foil retaining formation 70. The section 80 is separated from the remainder of the overcap by tear lines 84 along each side. These tear lines 84 are thinner plastics webs. A hinge 86 is formed in the overcap at a back of the removable section 800 nearest the centre of the top 64. A peak 88 can be moulded at the front edge of the section 80 to facilitate lifting of the section. A tab 90 is formed so that it projects outwardly from the remainder of the skirt 66 so it can be grasped to initiate the tearing of off of the section 800 and subsequent opening by pivoting the section 800 about the hinge 86. When the section 800 is opened in this way, the foil will be torn as it is lifted by the section 82 of the foil retaining formation 70.

The tab 90 can be clipped right over out of the way of the user's mouth by clipping it over the edge of the skirt 66 opposite the opening. After opening, the can can be closed by bringing the section 80 back over the opening.

An alternative style of can end closure is illustrated in FIGS. 13 and 14. Like reference numerals are used for similar parts. In this embodiment the overcap 62 does not have a continuous upper surface but exposes parts of the foil membrane 68. A portion 94 of the upper surface of the overcap 62 is moulded in such a manner that it can be removed by gripping on a pull tab 96. In this embodiment the foil retainer is a wall formation 98 underneath the portion 94 indicated by dotted lines. This formation 98 does not need to be a closed circle as shown in previous embodiments. There may also be more than one foil retainer edge. This type of can end can be adapted for various types of spout construction.

It will be appreciated that given the concept of a foil retainer with an edge welded to the foil membrane on a part of an overcap that is removed during the opening process, the skilled man will be able to design various patterns and configurations for such edges that facilitate tearing and lifting of the required parts of the foil needed to leave a convenient drinking opening. The removed parts of the foil held by the foil retainer edges can also be designed to have aesthetic shapes.

Variations

The closure as illustrated in FIGS. 5 to 10 is intended for use with a 33 mm bottleneck but it will be appreciated that it can be used for wide mouthed bottles and smaller drinks bottles as well as adapted for wide mouthed jars, cartons, cans and thermoformed containers of all manner of diameters.

Additional tamper evidence can he provided by a removable or breakable tab adjacent the peak 34 locking the overcap to the adjacent wall of the base. In the can end embodiment, a similar breakable tab or other tamper evidence structure may be provided. The can end embodiments can also be used on a variety of can diameters.

Moulding the overcap 6, 60 or 62 out of a see through or clear or clarified plastics material also offers additional visual tamper evidence.

It is therefore possible to provide feedback by visual, audible and touch mechanisms to reassure consumers that the products supplied with the closure has not been previously opened or tampered with. 

1. A closure comprising a spout defining an opening and a foil membrane closing the opening, the closure having an openable section with a foil retaining formation terminating in an edge bonded to the foil membrane to define a removable portion of the foil membrane, the foil membrane also being bonded to a non-openable section of the closure before application to a container; characterised in that the closure has means for engaging it over an open end of a container; in that the foil membrane is held inside the closure in order to provide a border adapted to be induction heat sealed to the container; and in that the openable section is pivotable relative to the non-openable section of the closure.
 2. A closure as claimed in claim 1, characterised in that the foil membrane is bonded to a land on the non-openable section close to an edge of the opening in order to create a region of foil which is stretched between the land and an adjacent part of the foil retaining formation during the opening process to create an initial tear in that stretched region.
 3. A closure as claimed in claim 2, wherein the stretched region is opposite a hinge about which the openable section pivots open.
 4. A closure as claimed in claim 2, wherein at least one foil tearing tooth is provided between an edge of the opening and the land.
 5. A closure as claimed in claim 2, wherein a pull tab is provided on the openable section to apply an opening pressure in said stretched region.
 6. A closure as claimed in claim 4, wherein an edge of the opening is pointed in said stretched region.
 7. A closure as claimed in claim 1, wherein an openable section is an overcap.
 8. A closure as claimed in claim 1, wherein the openable section is adapted to be torn from a remainder of an overcap carrying at least a part of the foil retaining formation.
 9. A closure as claimed in claim 1, wherein the edge of the formation is continuously welded to the foil.
 10. A closure as claimed in claim 1, wherein the edge is intermittently welded to the foil.
 11. A closure as claimed in claim 7, wherein the edge is crenellated.
 12. A closure as claimed in claim 1, wherein the edge has a radius of less than 0.3 mm.
 13. A closure as claimed in claim 1, wherein the edge has a radius of 0.1 mm or less.
 14. A closure as claimed in claim 1, wherein the openable section has a peak by means of which the user can pivot it, the formation having a shape which converges to a tip aligned with the peak.
 15. A closure as claimed in claim 1, wherein the openable section has a peak by means of which the user can pivot it, the formation having a shape which defines tips spaced to either side of the peak.
 16. A closure as claimed in claim 1, made from a see through or clear or clarified plastics material.
 17. A closure as claimed in claim 1, wherein the overcap is attached to a container or spout by means of a breakable tab. 